1. Field of Invention
The present invention relates to a tubular part that can be used as part for an inflator for a restraining device for a vehicle.
2. Description of Related Art
Crimping and fixing an igniter to a housing is a well-known technology in the field of gas generators and the like.
In a gas generator, gas generated inside the housing during actuation is discharged from a gas discharge port formed in the housing and introduced into an airbag or the like. As a result, it is necessary to prevent the gas from leaking at the regions other than the gas discharge port. In particular, with a gas generator using a solid gas generating agent, it is necessary to seal the inside of the housing so as to prevent the solid gas generating agent from absorbing moisture over an operation period (about 10 to 15 years).
For this purpose, it is necessary to avoid the appearance of gaps when the igniter portion is crimped and fixed, and from the standpoint of preventing the igniter from falling out when a gas pressure is applied to the igniter during actuation, it is important that the igniter be fixed to the housing.
U.S. Pat. No. 5,571,271 describes an art for fixing structural parts of a gas generator by crimping. An outer shell container of a gas generator housing described in U.S. Pat. No. 5,571,271 has a tubular shape and, as shown in FIGS. 7 and 8, a taper 39 is formed at an opening end 38 at one end portion on the inner peripheral surface thereof. The ratio d1/d2 of the thickness d1 of the opening end portion 38 and the thickness d2 of a base portion is disclosed to be 60% to 80% (column 4). When the opening end portion is crimped, a crimped and fixed structure having a comparatively large curvature is obtained, as shown in FIG. 8, thereby inhibiting the appearance of cracks in the crimped portion.